The present invention relates to drainage and, in particular, to improvements in the drainage method and the strap drain materials therefor.
The inventor discloses in the U.S. Pat. No. 5,934,828 a drainage method and strap drain materials adapted for use in the soil conservation on mountain slopes, the underground drainage on orchards and farms, and the drainage system in tunnels, road bases and building basements. This is brought about at the openings of drain channels of the materials by means of capillary action to absorb in water from the soil, by the difference in elevation between the two ends inside the channels of enlarged area and the partial siphoning force so produced thereby promoting water absorption and collection for discharge. Samples of such materials on testing have now been found to contain the following problems, which need to be improved:
(1) because the drain materials are of a sheet like strap type, the hollow portion in section occupies a considerable area, which more often exceeds that of the solid portion. On production, due to small resistance to pulling, the materials sometimes break on pulling or the channels are deformed and are therefore not suitable for high speed long measure continuous production. On use, because of relatively small strength of the pull resisting structure, the entire strap is easily pulled crack. PA1 (2) It is very difficult when the drain materials have to be connected laterally. Also, by means of connecting it is inconvenient and unreliable by means of connecting members affecting the construction works. Furthermore, when embedded in soil it also produces relative slip easily because of the small frictional ground gripping force of the soil.